1. Field of Invention
This invention refers to an improved mechanical control device of ball valve type valve systems. More in particular this invention refers to an improved mechanical control device of ball valve type valve systems, for extinguishers and for containers fitted with opening and closing means in general for the controlled delivery of a pressurized fluid.
2. Description of the Prior Art
As is known, the opening and closing of ball valve type valve systems is normally achieved by the rotation of a hand-wheel which causes the rotation of a valve body. The valve includes a valve ball having passages which intersect with one another at a right angle and which set at least two passages into mutual communication: one of which is the opening to the gas cylinder containing the pressurized and generally liquified gas, and the other is a discharge and delivery port of the fluid.
These known hand-wheel type control devices have certain drawbacks and limitations. The most common of these drawbacks is caused by the hand-wheel itself, or by other means which require rotation to effect the opening and closing operation. This rotation necessarily requires manipulation which cannot be performed by the same hand that supports the gas cylinder. This drawback is particularly experienced in the case of an extinguisher which must be handled rapidly and with reasonable accuracy to direct the extinguishing medium in the most appropriate direction to strike the base of the flames to be extinguished.
"Needle" type valve systems are also known in which the hand-wheel is replaced by a lever mechanism. However, the known needle type valve systems do not guarantee the necessary air tightness to prevent the pressurized fluid contained in the extinguisher cylinder from escaping. Furthermore, in these needle type valve systems, the discharge is not efficiently controlled and gradual. An additional drawback is caused by the fact that in the known needle type systems parasitic phenomena are created, termed "water hammer", caused by the sudden interruption of the liquid flow, for example when extinguishing with water from the local water mains. In these instances, closure of the valve means causes a sudden stoppage of the water column up-stream, causing the "water hammer" effect.